1. Field of the Invention
The present invention relates to a method for manufacturing a glass substrate for a display that is used for flat panel displays such as a liquid crystal display, a plasma display, an organic EL display and the like as well as a glass substrate and a display panel.
2. Related Background Art
Conventionally, in the manufacture of a flat panel display employing a liquid crystal display panel, a plasma display panel, an organic EL display panel or the like as a display panel, a fine thin film pattern is formed on a glass substrate by photolithography with use of an exposure device.
Display panels used for these flat panel displays are manufactured through various processes such as conveyance of a glass substrate, film formation, photolithography, etching, doping, wiring, or the like after the glass substrate is introduced to a manufacture line. In each process, panels including glass substrates are placed in an environment in which panels can be easily electrified due to various factors. For example, when the glass substrate is introduced to the manufacture line, slip sheets are peeled away and removed from the glass substrate when taking out glass substrates one by one from a plurality of the glass substrates that have slip sheets sandwiched therebetween and are layered on each other. At this time, the glass substrates are easily electrified at the time of removing the slip sheets. Also, in the case where a device for manufacturing a semiconductor is used in order to form a film and the like, the glass substrate is placed on a placement table to form the film. At this time, electrification due to an air current, a contact electrification, or a peeling electrification is likely to occur on the glass substrate. The peeling electrification is electrification that occurs in the case where the glass substrate that is in close contact with the placement table is removed from the placement table.
Such electrification causes various problems, and therefore it is preferable that the glass substrate is not electrified as much as possible. For example, in the case where a thin film transistor (TFT) and a wiring pattern are formed on the glass substrate, the wiring pattern may be damaged or may peel away due to foreign substances such as motes and dust adhering to the glass substrate or the wiring pattern due to electrification. Also, there is the case where the TFT or the like is damaged due to electric discharge of accumulated electric charges. Also, there is the case where the glass substrate adheres to the placement table due to the abovementioned electrification, and there is also the case where the glass substrate is cracked when it is removed from the placement table.
A method for removing electricity from the electrified glass substrate using an ionizer under such situations is known (JP 2009-64950A). Also, an exposure device that has a stage on which a substrate to be processed (glass substrate) is placed and that has a surface of 1-100 μm surface roughness is known (JP 2007-322630A).
In contrast to this, a glass substrate for a display that is capable of suppressing electrification when the glass substrates in a contact state are subjected to a peeling process are known (JP 2002-72922A). Specifically, the glass substrate is a glass substrate for a display that has a plate thickness of 0.3-6 mm, and an average value of WCA (filtered center line waviness) of 0.03-0.5 μm that is measured, in a measurement length of 200 mm, with a stylus type surface-roughness measuring instrument that uses a phase compensation 2RC band-pass filter having a cutoff value of 0.8-25 mm. It is assumed that the glass substrate is capable of reducing a contact area between the glass substrate and the placement table and also suppressing the electrification.
Furthermore, it is known that the glass surface is chemically processed so as to have an arithmetic mean roughness Ra of 0.3-1.5 nm (JP 2010-275167A). Specifically, it is assumed that the contact area between the glass substrate and the placement table can be reduced by setting the arithmetic mean roughness Ra of the glass substrate to 0.3-1.5 nm, and as a result, the amount of electrification can be reduced.